HT engine 66cc Piston ring compresser

Discussion in '2-Stroke Engines' started by buzbikebklyn1, May 23, 2011.

  1. buzbikebklyn1

    buzbikebklyn1 New Member

    DANG IT! that the second time I broke a ring using my old small bore piston ring compressor...
    Whats the hot set up so I dont break any more rings...?
    I was being VERY careful but that ring keeps hanging up at the bottom of the cylinder.
    Now im stuck waiting on replacement rings.
    How about a little help here?

  2. Al.Fisherman

    Al.Fisherman Active Member

    With a extra pair of hands, we use our fingers. My son lines up the top ring, paying particular placement (stud in the ring grove) squeezes it and I tap on the cylinder then onto the bottom ring. Have you noticed that both ring groves has a alignment pin. This is so the rings stay in place and don't align up with the intake and exhaust ports.

    Last edited: May 23, 2011
  3. buzbikebklyn1

    buzbikebklyn1 New Member

    Thanks for the advice, unfortunately we tried that one and it still broke as we tapped the cylinder down.
    We oiled it.
    I made sure the registration pins were correctly aligned...
    I champhered the bottom of the cylinder skirt.
    I made sure the ring compressor band was sitting perfectly flush with the piston and concentric to the cylinder skirt.
    We were very careful and yet the little S.O.B. still broke...GRRRRRR!
    (throw tools at wall here)

    I did everything but take the little bugger to dinner and a movie and it still broke!

    Then I remembered the old piston ring end filer my dad had stashed away under his bench...
    Its a little hand cranked deally...Its got a flat top with a small circular file and a few registration pin holes in the top, not rocket science...
    Nothing trick...
    60 seconds spent filing the end gaps on both rings did the trick, it slid right in with no problems...
    That got me worried that the piston ring end gaps were now to large...
    A leak down test after assembly showed almost perfect ring seal...
    Thanks Pops were ever you are...the mans been gone 20 years and hes still taking me to school.

    EUREKA! its alive!

    I wanted to kick myself for not realizing that no one ever bothered to match the rings to the cylinder and piston...
    Lesson learned
    Sometimes the old ways are still the best.
    Last edited: May 23, 2011
  4. Al.Fisherman

    Al.Fisherman Active Member

    Whenever re ringing a cylinder, the first thing to do is slide the new rings down into the cylinder (no piston) and check for fit. Just because you buy new parts doesn't mean you got the right parts, and then there are mistakes in packaging. I have had to file a ring years (oversize ring set) ago so that I had the clearance I needed.
  5. Skyliner70cc

    Skyliner70cc Active Member

    how did you do your install? was the piston installed to the connecting rod when you installed the rings and then pushed down on the head to get everything together?

    What I do is remove the piston to install the rings and get it seated on the head. i push the piston into the head just enough for the second ring to clear then i take the assembly and lower it onto the engine and line things up so I can install the connecting rod-wrist pin and c clips. no need for an extra set of hands or special tools.
  6. buzbikebklyn1

    buzbikebklyn1 New Member

    Excellent idea Skyliner... that would also solve the problem.
    It would also make it easier to follow Al.Fishermans advice and ALWAYS square up the rings in the empty cylinder to check for end gap clearances.

    The clearances are all over the road on these little engines... MEASURE ALOT, CUT OR FILL AS NEEDED...

    Ever try to use the crappy little gear puller they give you with the engine kits to remove the crank gear?
    OF COURSE it stripped out!
    I welded it to the gear to get it off and threw both in my draw, since a new crank gear costs like what?$ 5? its not worth trying to find a gear puller to fit under it to get it off with out cracking the cases.

    I guess its just the 30 years or so of building big twins and hot four cyl. motorcycle engines out of good parts.
    I kinda expect stuff to fit if it was ordered correctly...

    BUT NOOOOOOOO... not with these little headaches...

    I've found a machine shop that's got CNC capability, (and thats a little slow on business) and I'm going to hand them a brand new GT5R engine in pieces (cases, barrel and heads)
    and have them copy it in billet aluminum with revised mounts and larger bolt holes.

    I like the HT engine lay out, its perfect for a bicycle, in my opinion it just fits better than the Morini or those weed whacker looking 4 strokes, now we just have to build a better one, but the same external dimensions.

    Any one interested?
    I have to order at least 5 of them to get the machine shop to do it.

    Thanks for all the advice...
    Last edited: May 24, 2011
  7. Skyliner70cc

    Skyliner70cc Active Member

    i'd be interested in a cnc engine only if they used the ht engine dimensions for mounting and used the morini porting/timing w/ reed valve intake for the internals...that'd be a win-win situation.
  8. buzbikebklyn1

    buzbikebklyn1 New Member

    Proposed modifications for a new HT type billet engine

    Skyliner70cc... my thoughts exactly.
    As luck would have it i just happen to have a Morini "S" series engine to take measurements off of.

    I took one of my old HT cyl. barrels and laid it out next to the S6 morini, broke out the measuring tools and went to work,

    Its a no go for the Morini reed block assembly to be fit into the base of an HT type cyl. barrel and port configuration.

    This Mod. would raise the cyl. height and would be to wide to fit in between the head studs and would totally fill the area behind an HT motor
    (were do we now put the carb with out seat tube or shift kit clearance problems?)
    HOWEVER... Morini parts aren't the only game in town.
    I'm looking for a smaller reed block assembly that will fit within the HTs existing external dimensions.
    Now for the intake and exhaust port configurations...

    As we all know the mighty Morini has its exhaust port spigot smack dab in the middle of the front of the cyl. giving us all a hard time in head pipe fabrication and routing.

    The HTs exhaust spigot is off set to the left side of the engine making it much easier to plumb the head pipe to clear a bicycles down tube.

    The HT has its intake and exhaust ports located in the sides of the cyl. barrel, the Morinis are front and rear... again a miss match.

    Certain ideas and configurations will be useful...
    but I'm not trying to create a mini Morini here.

    The entire reason for this exercise is to build an HT that has a bit more guts and reliability... and yet keep its small size.
    It needs to be able to take a few more points of compression with out the crappy castings letting go.
    Thats why its being copied in billet...
    Its always struck me that a 50cc Morini puts out more power than a 66cc HT.
    Bigger port configurations for a "super" HT will be altered accordingly.

    How about some kind of mechanical crank start lever maybe?
    Keep the ideas coming guys.
    Its all good.